The GN produced that power with accessories on so it makes more power after parasitic loss then the Buick 350. 72 350-4 rated 180/275
Correct! 1972 350-4 was rated at 195/290 though. Power started to decline after this for reasons explained earlier. OK...now take those 1972 figures (pick whatever numbers tickle your fancy even if they're not spot-on based on our memories) and calculate in taxable hp as was given by me in a previous post (about 74 hp based on the TH350 trans instead of the ST300 trans, PLUS the accessories (including the AC)--and even this number of 74 is a 'guestimation' based on limited information, but seems to be fairly close) and add it to 195 and tell me what you get. Is it close to the 1971 (the year prior to using SAEnet measurement method) figures? I think it is! if 245, 276, whatever you want to use, is SAEnet hp, how much do you suppose it would make at the flywheel? 245 SAEnet hp is vastly different than 245 flywheel hp. I think we may be on to something here! Also bear in mind that the 'taxable' power would also vary based on engine, car, transmission, accessories, etc. and would likely be more accurate to convert it into a percent rather than a static number to be used across the board for all. This number was applicable to the Buick 350 and the cars it came in for those years. EDIT: maybe this will help-- Take the numbers I stated earlier about 360-370 ft. lbs. and 250-260 hp being achievable with a low comp engine and the Crower level 2 cam that you disagreed with. IF we were talking SAEnet, then you'd be 100% spot-on (since those are GN numbers @SAEnet), but I was talking about flywheel numbers. This is why I felt it was very important to distinguish between the two, and was long-overdue because I see confusion on this all over the place here on the boards. It didn't seem like a big deal at the time because we would talk about it as an afterthought, but now that it has become the main subject, I felt the distinctions were needed.
If you are comparing apples to apples, then the top end flow is what determines the power curve. A tiny bit of compression loss in the pump gas safe region is easily overcome by trapping a little more cylinder pressure, VE, cam, etc.. I hope this contributes to the OP's query's...
Aww heck, I think I'll dyno my 65 skylark. It has a 73 2bbl 350 with advanced timing, points dist, manifolds, st300, true duals with X pipe. If nothing else it'll give me a good baseline for other mods and hard data for y'all to argue about. I'd like to know what it makes before I add a 4bbl intake and FITECH.
That would be interesting to see what it reads,. I think you could see big increases with .030 or .040(8.7/8.9 compression) shave off head with that setup. And Gary , can you get more info on the sae measure change, , Wikipedia claims both at crank but one with accessories. https://www.google.com/url?sa=t&sou...4I5ah1We1H6YbaJFA&sig2=tSF-mYhNOV00j2gU5MvYpg
Don't tell Gary who likes to drive above the legal speed limit, but a trans swap would of gained you WAY more seat of the pants and actual get up and go if you changed the trans instead of the engine from stop and go driving than the engine change you did. :Brow: Derek
When I swapped the ST300 in my '68 skylark for the TH375, it did have (slightly) better acceleration in 1st gear, but shifting from 1-2 and you could feel the extra power drain on the car that the larger transmission had. Shifting from 2-3 felt like it was going uphill against a strong headwind when comparing it to what it felt like with the ST300. So yeah, take off is better, but after you're out of the hole, performance suffers. We all drive our cars taking off at full throttle though right? There's no cruising, no going down the road at any speed, just launching. In this case, the trans swap would be better. If you want to put more power to the ground at any speed, use the ST300. It's not a drag racing trans, but for the street, it's hard to beat. This part boils down to preference I guess. I have had nothing but great experience out of my ST300's. I even had one behind my '70 455 and it never had any performance or durability issues. As far as finding more info on the SAE rating methods, the internet is your friend. Some sources state net and gross measured with just accessories, not transmission. In the early-mid 70's when the different method was introduced, it stated in the manuals that it was WITH the transmission, so it took off even more this way. Semantics and nitpicking aside, what it boils down to is the older rated engines showed raw power, and the later figures showed a more realistic, 'real-world' rating.
I typically find much greater gains on lower compression engines by verified flow bench work and logical breathing improvements (cam, intake, headers) than simply raising compression a small amount on a stock headed, mild cammed engine having the same external mods. There really isn't even a comparison here... Forget rating methods and comparing emission choked factory engines to earlier ones. I hope this steers the OP the right way.
I see now where your ST300 bias comes from now. A TH375 is basically a TH400 with the same gearing and using the same amount of HP to run as a TH400 without all of the strength of a TH400. If you swapped in a TH350 those many decades ago your opinion would be totally different towards that slug of a trans the ST300. Even better gearing would be a 200R4 or 700R4 to swap in that would of been better noticeable performance upgrade than a sbb 300 to sbb 350 engine swap. I can't stress this enough, THE ST300 IS A TURD OF A TRANMISSION because of its crappy gearing. Swapping in a TH350 that's only takes what was it, 4 HP more than the ST300 to run, which the pulling out into traffic MORE than makes up for that measly 4 more HP that the TH350 uses because of its better gearing where its driven more! Now swapping in a TH375 with the same gearing as the TH400 which is less gearing than the TH350 and it uses as much power to run as a TH400, I can see why your small block car felt like a slower turd higher in the MPH than the ST300 because instead of just 4 more HP, it took away about 12 more HP from the already low HP rated small block. But wait, with all the torque that a sbb 350 supposedly makes, loosing that miniscule amount of HP shouldn't make barely a dent of a difference with these torque monsters or so I have read that they are anyway.(actually in this very thread) So in conclusion, THE ST300 IS A TURD!! And is what was slowing the car down more than the sbb 300.(period) A rear gear change would of even been a better performance upgrade than a sbb 300 to sbb 350 swap. Derek P.S; Stating that the ST300 trans is a turd is just my opinion and not meant to be a personal attack on anyone that is in love with that turd of a transmission.
I don't have anything to compare my st300 to. I know my car runs like a turd though My last 2 cars were a 2013 Camaro SS m6 and a 1996 Vette m6 (modded) I'm serious about taking my car to the dyno. I'd like to see what it makes as is. Then take it back after the FITECH swap. The car ran like a huge turd when I got it, really bad. Its much better now, a smaller turd I guess and actually drivable but that 2bbl 350 isn't overwhelming me or the tires anytime soon.
I did the switch from a 350 trans to a 2004r trans, I would run 79 mph in the 1/8 with the 350 trans and a 3500 convertor and it was on the loose side, I could foot brake to 3000 rpm, had 60 ft times in the 1.75's. Ran 13.50 Now bring on the 2004r trans, Still run 79 mph in the 1/8 which I feel is due to the lower 1st gear in the trans. The stall is now at 3000 rpm and is a lot tighter, can't foot brake to 3000 maybe 2500 rpm. But the 60 ft time went up to 1.90 and the ET has moved up to 13.60. That ST300 trans would not come out of the hole as fast as the other two trans the gearing is too high unless you want to use a 4000 stall convertor. But, you could probably do 65-70mph in low gear with a 275 rear gear. We had a Nova with a Power Glide and it would do 65 in low gear and 115 on the top and that was a straight 6 with a mono jet. That thing would beat a lot of V8's though, That top of first gear would get them every time at 65 mph, heck maybe Gary does have something with that 300 trans LOL. This has a lot to do with camshafts, doesn't it? It's good information to know if you are building a hot rod, learn.
LOL!! :laugh::laugh::laugh: :shock::shock: So you understand what I'm saying I see. I don't think a FITech is going to make your engine run any stronger than the carb that's on it now, just a bit more efficient with possibly loosing a bit of low end torque unless you up the compression to make up for the increased CFM hole the FITech electric carburetor has. The sbb 350 engine can be built to run better and more compatible to the engines you're a custom to, using the right parts to do a performance build. Those parts will in NO WAY include "stock" replacement pistons tough, just so you know. PM me if you're interested in making your sbb 350 run closer to the power level of the more modern engines. Derek
Derek , the efi is some good stuff. On a stock engine won't see a lot but on a modified engine you will think why didn't do it sooner. My brother has my old 430 with my grand national trans and a Holley terminator efi. It made the 2 chamber flowmasters quiet with almost no drone and it tears thru the gears . The hotchkis suspension tries to bite but there's just too much torque. Defiantly worth looking at.
I have to agree that it would be the icing on the cake for a more performance orientated engine, probably not all that much better for a factory 2 bbl engine now just fitted with a 4bbl intake so the FITech will bolt on. A self learning self adjusting system will be better than any carb to make the air fuel ratios closer to where they should be on any different day. Driving from a low altitude to the mountains the same day the FITech would self adjust the A/F ratios to be closer to optimal whereas a carb would have the same jets in it from whatever altitude or A/F ratio it was adjusted to until the jets are manually changed again. Derek
If that's the only mod you are making then save yourself a ton of $$ and abandon the notion of it becoming a barn-burner due to the magic of EFI, LOL! Put the equivalence into everything below the intake and watch the magic happen. Sorry for any negativity!
It'll be worth the $75 to dyno it to at least get a baseline. I predict 150rwhp and 260rwtrq. Thats just a S.W.A.G. though. I really dislike taking the thread off track but its in another zip code at this point. That said, to try and keep with the original intent of the thread I 'may' put another cam in mine with some head work. That would really be interesting to see how it responds on the dyno before and after. I'm really back and forth on keeping the SBB in it. I think its a solid starting point but I dont want to sink a lot of $$ into it that could otherwise go to the BBB build. One combo that keeps getting mentioned is a crower or TA212, shave heads and a bit of home porting. This would give me another reason to go to the dyno for a set of before/after sessions. I did this many years ago with an m6 L98 corvette I had. Stock it put down around 218rwhp and 310rwtrq, trapped at 98mph. By the time I got rid of it I had it up to 104mph and 260rwhp. Those claims of 20 bolt on HP from XYZ mods were all bogus. Shorty headers, true duals and removal of cat was 9rwhp. Remove air pump and replace with an idle pulley, tune and cold air induction was about 4hp. Ported plenum, bigger runners and SLP base intake was a solid 16hp. Underdrive pulley was about 5hp. The rest was from a valve job, port matching, thinner head gasket etc. I would dyno it between mods. It was a slow bolt on build at best though. My stock LT4 corvette put down 305rwhp as delivered from GM and trapped 106mph. Hotcam, headers, gears, tune, electric water pump put it at 116mph traps. RWHP only jumped to mid 360s but to be fair I did lighten it about 100lbs and raised the rev limiter from stock 6300 to 6800rpm. It did not expereince float and I would shift at 6700. It really liked the gears and rpms. Trap speed and dyno runs can be used pretty effectively but it takes several of each to make a valid comparison. Just one run or one session doesnt help a lot. I like being able to see a trend over time. Lets be honest, how many people have really put a low compression SBB on a dyno. Its not like they are the pinnacle of the performance world or anything. They get very little attention so I doubt theres much out there other than marketing hype. There is some, but not a lot.
I know. The plan is to use the current SBB to power the car while I sort brakes, suspension, fuel injection, fuel delivery etc. The temptation is that I sometimes imagine myself putting a little bit of effort and money into the SBB since I think its in decent shape despite its age. If I could get it to an honest 270ish rwhp it would be enough to make the car fun.
That always makes it more fun to see your upgrades unfold into making more power. I did basically the same thing except I took my cars to the track to see the sum of the improvements. A sbb 350 will cost substantially less than a BBB 455 build. Some home porting if in you're up to that and about $4k would make a REALLY good sbb 350 runner, would cost less if you skip the roller cam if $4K is to much(A BBB could cost more than twice that depending on what is done to it). And when the sbb 350 TA Performance aluminum heads come out you can swap those on and see what kind of gains those are worth. 400 N/A pump gas rwhp shouldn't be a problem when the heads come out with the right cam to take advantage of them. High 11s if you get the rest of the car up to the task of running that time, like better trans and match the rear gear with torque converter, upgrade rear suspension for traction and don't forget to make sure the brakes are up to the task of stopping the car. Also a sbb 350 is about 200 lbs lighter than a BBB, take off another 60 to 70 lbs when the aluminum heads come out and 30 to 40 lbs for an intake that's over 300 lbs less than a BBB. If you want to set the engine up for boost, the sbb 350 block can handle more power than a BBB block with or without a jockstrap(a BBB 455 full girdle). The sbb is a decent platform to start with as long as you stay away from certain parts that have proven to make any sbb 350 run worse than from the factory! Which is pretty much what gave the sbb 350 a bad name for years now and why many have chosen to stay away from them. Fun stuff, like I wrote in the previous post, if you're interested in building a sbb 350 that runs better than a typical sbb rebuild, PM me and I'll fill you in on what it takes. :TU: Derek
